This invention relates generally to the field of processes for generating ionic particle beams, and more particularly to the field of processes for production of negative ions. Specifically, this invention comprises a process for high efficiency production of negative ions of hydrogen isotopes (protium, deuterium and tritium).
Considerable interest exists for the production of intense beams of negative ions useful for such applications as low energy kinetic studies, material properties studies, high energy accelerator applications, production of fast neutral beams for controlled thermonuclear fusion studies, energy beam weapons devices, and other processes requiring directed energy beams.
Existing processes for producing negative ions fall into four broad categories, including double charge exchange for converting a positive ion beam into a negative ion beam, surface generated negative ions from charged particle bombardment, laser focus generation, and electrical discharge generation.
Prior art devices and method for the production of negative ion beams are lacking in capability for generating beams of sufficient intensity suitable for applications such as ion sources, or generation of fast neutral beams.
Production of negatively charged hydrogen isotope ions according to the present invention comprises the process of cooling (reducing the translational energy of) molecular hydrogen gas to a temperature of about 200.degree. Kelvin; vibrationally exciting the molecules of the cooled gas by an excitation means, such as electrical discharge, electron beam, or laser irradiation; and dissociating the translationally cold and vibrationally excited molecules by electron impact to form one neutral hydrogen atom and one negatively charged hydrogen ion (H.sup.-) from an impacted molecule (e.g., H.sub.2). Alternatively, the gas molecules may first be vibrationally excited by heating through thermal or electrical discharge means and then cooled to a reduced translational energy either by gas dynamic expansion or by heat exchange techniques prior to dissociation by electron impact. The processes of this invention may be applied to all isotopes of hydrogen (i.e., protium (H.sub.2), deuterium (D.sub.2) or tritium (T.sub.2)), and to isotopically mixed species (i.e., HD, HT, and DT).
Generation of negative ions using the processes of the present invention therefore comprises control of non-equilibrium conditions in the vibrational, translational and rotational energy states of the hydrogen molecule to achieve high rates of production of negative ions of hydrogen isotopes.
It is, therefore, an object of this invention to provide a process for efficient generation of negative ions of hydrogen isotopes.
It is a further object of this invention to provide a process for high rate generation of negative hydrogen ions.
These and other objects of the invention will become apparent as the description thereof proceeds.